Discoloration above henley cassette stove

[Kylebolts]

Hi there,
I had a new henley cassette stove installed and there is some discoloration now above the fireplace. I had the wall plastered and painted after the installation, so maybe the paint was too fresh? In any case, can someone share some advice on why this happens and what I can do to prevent it? The cracking in the photo looks to be the paint cracking and doesn't look to go deep into the plaster.
Thank you!

 

[vbu]

You can prevent it by not burning.
My parents used a special type of paint that's very slick, and that reduces it. I think they repaint that area every other year.

 

[Kylebolts]

You can prevent it by not burning.
My parents used a special type of paint that's very slick, and that reduces it. I think they repaint that area every other year.

thank you! So is it from smoke when opening the door or from heat? I'm going to look into a heat resistant / easy to clean paint.

 

[EbS-P]

How hot does the wall get. I’m trying to decide if it’s smoke or heat damage.

 

[stoveliker]

And exactly where does heat come out of the slit there?

 

[Corey]

Just doing some quick browsing, I see 'cassette' is a style of the stove, but not necessarily the model. Some similar Henley models I see require 600mm of non combustible material 'such as brick work' above the stove.

This was the closest I could find, where they discuss on p.11

https://henleystoves.com/wp-content/uploads/2018/09/MANUAL_APOLLO_5_2018_FINAL.pdf

You say you "...had the wall plastered and painted..." so not sure where that fits on the 'flammability' scale. If the wall was originally brick then it might be OK. Here in the states, a 'wall' would typically be 2x4 studs with sheetrock (or blueboard in case of plaster) - so that would generally not be considered non-combustible. Older style walls with wooden lathe and plaster would definitely not be non combustible.

I guess if it is only smoke, then there would be a few options... extend the flue so less smoke spillage when the door is open, possibly install a bit of a diverter lip at the top of the frame so smoke is diverted out and away from the wall, shoose a slightly darker paint color which doesn't show the smoke, etc.

Though if the wall is discoloring from heat, that seems to be a more major issue. First, be sure that it is all non-flammable construction at least 600mm above the stove. If that is the case, then the likely issue would be heat coming off the flue, so possibly install some high temp insulation or a heat shield between the flue and the wall.

 

[begreen]

Sheetrock and wood studs are considered combustible.

The discoloring appears to be following the flue system. After the stove is burning for a couple of hours, can you place your hand on the discolored area? If yes, for how long?